4″ Exhaust Thru-Hull, Black w/Flapper

4″ Exhaust Thru-Hull, Black w/Flapper (383-1200325) is a polymer marine wet-exhaust thru-hull fitting designed to route exhaust through the hull while using an integral flapper to help reduce water backflow when the engine is not running.

Key Features

• 4″ thru-hull exhaust fitting in black finish
• Includes flapper valve for added backflow protection
• Transom-mounted, wet-exhaust thru-hull style fitting
• Polymer construction helps prevent corrosion and eliminates painting/changing colors from saltwater exposure

Product Compatibility

• Marine wet exhaust systems
• Outboard/inboard exhaust discharge through hull (transom-mounted applications)
• Exhaust hose-to-thru-hull connection setups

Product Details

• Product title: 4″ Exhaust Thru-Hull, Black w/Flapper
• SKU: 383-1200325
• Manufacturer part reference: 1200325
• Color: Black
• Nominal size: 4.00″ (102mm)
• Ext. length: 3.25″ (83mm)
• Length: 7.75″ (197mm)
• Diameter: 6.00″ (152mm)
• Thru-hull length: 4.50″ (114mm)
• Fitting type: thru-hull exhaust fitting with flapper

Parts Desk Insights

Best Use Case: Use this thru-hull fitting when you need a corrosion-resistant, polymer exhaust discharge point for a 4″ wet-exhaust hose run and want flapper-type backflow protection at the hull outlet.

Common Issues: If exhaust flow seems restricted or the flapper doesnt seal properly, confirm the fitting orientation on the transom, inspect the hose connection and mating surfaces, and check for damage or debris around the flapper area (including any needed flapper replacement/service parts).

Related Products & Accessories

• Exhaust Hose Marine Wet Exhaust (4 inch) – Browse the Exhaust Systems collection for matching 4″ wet-exhaust hose and hose-clamp hardware.